Sustainability NK incorporates urban density, longevity, resource efficiency and return on investment into all of its designs. NK is known for reducing overall system loads and minimizing non-income generating spaces such as circulation, parking and mechanical areas. Projects are designed to consume fewer resources and use long-lasting materials that lower maintenance and replacement costs. NK is an expert in sustainable rating systems, such as Leadership in Energy and Environmental Design (LEED) and Built Green. The firm participates in the AIA 2030 Commitment, a program aimed at eliminating the need for fossil fuels in buildings by 2030.